A color photographic material is exposed and then color-developed, whereupon the oxidized aromatic primary amine developing agent in the color developer reacts with couplers in the material to give a color image. In the present system for forming color images, color reproduction by a subtractive color process is employed, where yellow, magenta and cyan color images are formed for the reproduction of blue, green and red, the former being complementary to the latter, respectively.
The indispensable features of couplers are that they not only are capable of forming dyes but the dyes to be formed have an excellent spectral absorption characteristic, the dyes have a high color density, the couplers have a high dye-forming speed, and the dyes to be formed from the couplers have high fastness to light, heat and moisture.
As yellow couplers capable of forming yellow dyes, compounds having an active methylene group are generally used; and acylacetanilide couplers and malondianilide couplers are widely known. The former are widely used as the most popular yellow couplers. They may form dyes having excellent color hue and color fastness, but they have drawbacks that the color density of the dyes to be formed is low and the color-forming speed is low. In particular, when the couplers are to be used as DIR couplers (which may release a development inhibitor when reacted with the oxidation product of an aromatic primary amine developing agent and which are used for the purpose of improving the sharpness and color-reproducibility of the images to be formed), the drawbacks are fatal.
Examples of improved yellow couplers which are free from the above mentioned drawbacks include azolyl acetate couplers described in JP-A-51-104825 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") and azolylacetanilide couplers described in JP-A-52-82423, 1-233452 and 2-28645. However, it is desired to further improve the couplers with respect to the fastness of the dyes to be formed as well as to the dye-forming speed.